The invention relates to an unmanned aerial vehicle, in particular to an unmanned aerial vehicle relay system. The unmanned aerial vehicle comprises a camera module, an image transmission module, a power module, a GPS positioning module, a flight control module and the like. Two flight modes of manual remote control and unmanned aerial vehicle autonomous flight can be achieved by carrying the relay system. In the flight process of the unmanned aerial vehicle, video information shot by a vehicle-mounted camera can be transmitted back to a ground control platform in real time. The unmanned aerial vehicle has wide application prospects, the cost is low, and the unmanned aerial vehicle can be assigned to the very bad environment to carry out tasks without worrying about the personnel loss.